[maddogjohnson]

I've read on many websites about the 3g alternator conversion, but have yet to come across something that I think adequately answers a question I have about the use of the stock wiring off a donor car.

The diagram that is often referenced shows a 175A megafuse with the comment: "The charge wire MUST be at least 6GA capable of handling 130+ AMPs to prevent fire or damage due to overheating."

I pulled a 3g alternator off a 6cyl 98 Mustang along with the wiring harness. The wiring harness has a sizable wire (6GA?) running off the B+ terminal and it splits into two 12GA fusible links that come together to form a ring terminal.



Why is the original B+ terminal wiring, with fusible links, that was used on the 130A alternator in the 90's car, not adequate to bolt directly to the solenoid on the 60's era vehicle?



This post says you will need to upgrade the wiring but does not state why.

Thanks!

 

[Driveway]

There is a pretty good article on all the generations of alternators in the July 2014, Mustang Monthly, page 30. As the newer cars came along with more electronics, the possible total power consumption got a lot higher than our older cars. If you have added extra electrical demands like a big sound system, electric fan, AC, headlights, etc. then the older wires just can't support all of that at once. One page 34 there are several warnings about upgrading the wiring to prevent fires caused by overheating.

 

[rex1965]

Okay, here's my 2 cts. With my 50+ years of electronic experience and my years of working on cars, I don't see any reason why the original wiring that came with the alternator wouldn't work, the fusible links are not to protect the wiring in the car, but to protect the wiring from the battery to the alternator and the alternator from creating a fire when diodes short in the alternator or some other short in the alternator and cause battery current to flow from the main wire through the fusible links to the alternator, so without the fusible links, a battery capable of 400+ amps with a dead short, something is going to get red hot and melt, and a fire is possible. The original wiring in a classic mustang was designed for the accessories in them, if you are adding additional accessories, then you should install relays with fuses to take the additional load off the ignition switch and the original factory wiring. Good Luck.

 

[HiPerformance28]

plus1..gif Rex1965. Relays are good things.

 

[maddogjohnson]

I finished up installing the 98 alternator and wiring harness today.

I used the run with the fusible links as is and just did a little stripping, crimping and connecting to get the other two wires hooked up where they needed to according to the diagram. I found this post to be most helpful in explaining what to do with the wires.

The pulley did not need to be shimmed at all. I dug through a bucket of nuts, washers, screws and bolts to find a bolt long enough to go through the lower mounting hole that I could put a nut on the back side.

Lights are noticeably brighter. My battery was fully charged at idle with every light in/on the car on (except fog lights), heater at fully blast and windshield wipers on. I do not currently have a working radio or my A/C system installed.

I swapped in a different engine wiring harness so I could finish up wiring for my fog lights. All I have left for them to work is solder one wire back onto the fog light switch.